Based on past experience, the driver pobably isn't the issue. This is likely an issue with motherboard support to the x16 slot since the adapter works in the x8 slot.
I think designers might be thinking about video adapters when they add BIOS support for the x16 slots, because I have heard reports of some other motherboards with the same type of issue with other adapters. Then other boards will take a NIC in the x16 slot and work just fine.
There might be a newer BIOS that could take care of the problem, or there might be some configuration items in the BIOS for that slot that you could set differently.
I hope these thoughts help you figure it out.
I think you're right. This slot is clearly intended to be a video slot and I have updated to the latest BIOS but no delta in behavior.
The really ODD thing is that if I have LINK at boot time on a port then it will function properly. OR if I go into the hardware manager and change a mode setting on the Advanced tab, something that causes it to delay or appear to 'think' before closing the dialog after I click OK, then it also works OK from that point on. So it obviously can work properly. I just need to determine the magic formula to get it to do that unattended at boot time when there is no link on the port. If anyone has any additional thoughts, links or guidance for a workaround it would be appreciated. I'm stuck.